PNNL

Abstract

Treaty monitoring gas measurement systems that measure radioxenon typically report results as an activity concentration, which is the measured radioxenon activity divided by the amount of stable xenon present. While the nuclear activity uncertainty has been studied in detail and is driven primarily by counting statistics, the uncertainty for the volume measurement has been considered in less detail. A framework for a more complete consideration of the uncertainty for the volume measurement has been developed. This type of analysis can help drive the system requirements for the volume quantification while the system is still being developed or added to advanced fielded systems. Depending on the accuracy requirements for the activity concentration, the volume quantification measurement and analysis can be developed to a suitably high level of accuracy. Nominally, it is best to have the activity concentration uncertainty limited by the uncertainty of the activity measurement because it tends to be fundamentally limited by the counting statistics. Volume quantification should be performed more accurately so that the activity concentration uncertainty is not degraded from the counting statistics. This paper will describe in detail a stable gas quantification uncertainty analysis for a xenon monitoring system.